Cobalt chromate complex

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

The crude substance is their recrystallised from water containing acetic acid. The compound was originally believed to exist in two isomeric forms, but Jorgensen found the crystalline form depends on the concentration of acetic acid used for crystallisation, inasmuch as rhombic leaflets separate from hot dilute acetic acid, and from hot concentrated acid the substance separates in yellow-brown needles. The complex is sparingly soluble in water, and gives no precipitate in aqueous solution with silver nitrate or potassium chromate. If treated with cold hydrochloric acid it is transformed into chloro-dinitro-triammino cobalt, [Co(NH3)3(N02)2Cl], and if warmed with concentrated hydrochloric acid gives diehloro-aquo-triammino-cobaltic chloride. 

The apparent simplicity and virtual certainty of Kurtz assumption are somewhat clouded by results obtained on complexes of hydroxyethylethylenediamine and similar ligands, for determined efforts have failed to reveal any of the normal reactions on the part of the free alcoholic function in complexes of cobalt (III) with these ligands (24, 25). In contrast, Krause and Goldby have esterified the free hydroxyethyl group in bis (2-hydroxyethyliminodiacetato) chromate(III) (46). 

Double Chromates.—Several double chromates containing cobalt have been prepared. Ammonium cobalt chromate, (NH4)2Cr04. CoCr04.6H20, is obtained by interaction of ammonium chromate and cobalt acetate in aqueous solution at low temperatures,6 and the corresponding caesium, cobalt chromate is known.6 Other complex derivatives have been described.7... 

Complex formation between cobalt(ii) and pyridine-2-aldoxime has previously been reported to be a slow process. The reaction has now been reinvestigated, and the new study shows that the mechanism is not so simple as was believed. It probably involves redox processes, in which finally cobalt(iii) is formed. Ligand exchange of peroxide between hydrogen peroxide and tetraperoxo-chromate(v) ion, [Cr(02)4] , has been studied and gives relevant information for the mechanisms of tetraperoxochromate decomposition reactions. ... 

Another example of the photoassisted substrate conversion due to a short-lived intermediate in the ground state is shown in figure 6. Chromic acid esters form chromium(V)/alkoxy radical pairs within the photochemical primary reaction. In the presence of such iron(III), cobalt(III), or copper(II) complexes which are able to interact coordinatively or by second sphere interactions with chromium(V) within the radical pair cage reoxidation to chromate(VI) occurs under simultaneous reduction of the metal complexes to corresponding iron(II), cobalt(II), and copper(I) species, respectively. Unfortunately, the efficiency of this photoassisted reaction is limited by... 

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